How Font Size Affects Reading Fatigue on Screens

Text that's too small makes you lean in, squint and focus harder, and over a long session that adds up to tired eyes, a stiff neck and headaches. Making text bigger is one of the simplest ways to make screen reading more comfortable.

Why small text is tiring

• More focusing effort. Your eyes work harder to separate small letters, especially on lower-resolution screens.
• Leaning closer. Moving toward the screen strains your neck and brings the screen closer than is comfortable for long periods.
• Less blinking. People blink less when concentrating on a screen, which dries the eyes. Harder-to-read text makes this worse.

A good size to start from

On the web, 16 pixels is the usual default for body text, and many people read long articles more comfortably at 18 to 20 pixels. The right size depends on your screen, your distance from it and your eyesight. A simple test: you should be able to read comfortably while sitting back in your chair, at about an arm's length from the screen.

To check what size a site actually uses, Font Detector shows the font size, family and weight of any text you click.

Size isn't the only thing that matters

• Line length: lines of about 50 to 75 characters are easiest to follow. Very wide lines make it hard to find the next one.
• Line spacing: around 1.5 times the font size gives the eye room. The line height calculator works it out.
• Contrast: dark gray on white or light text on dark gray is easier than very faint text. Test with the contrast checker.
• Font choice: fonts with a tall x-height and open letters stay readable at smaller sizes.

Make text bigger in Chrome

• Zoom one site: Ctrl and + (Cmd and + on Mac). Chrome remembers the zoom level for each site.
• Change the default: Settings → Appearance → Font size and Page zoom.
• Use Reading mode for long articles, where you pick the size and spacing.

More options in how to increase font size without zooming the whole page and custom line spacing in Chrome.

Other habits that help

Take regular breaks: the American Academy of Ophthalmology suggests the 20-20-20 rule, looking at something 20 feet away for 20 seconds every 20 minutes. Keep the screen slightly below eye level, and match its brightness to the room. If your eyes stay tired despite bigger text, see an eye doctor; you may need glasses for screen distance.